Since external apparatuses such as tablet PCs, notebook PCs, cellular phones, televisions, etc, are small in volume and light in weight, they can present good features in carrying and moving. However, theses external apparatuses are made into a light, thin and compact configuration, thus, as compared with desktop computers, their extension is not good. The extension means extended function, such as printing, scanning, modulating, demodulating, reading data from various mediums, etc. In order to be connected to external devices such as printers, scanners, modulator, demodulator, CD-ROMs, etc, it is necessary to provide interfaces corresponding to these devices respectively on the external apparatuses. But in the external apparatuses required to be miniaturization, it is hardly to insure spaces for these interfaces. Therefore, aiming at such disadvantage, it has developed an electronic apparatus used for extending functions of an external apparatus. The electronic apparatus is, for example, a dock, an external connection device, a cradle, a holding device and a supporting device, etc. When the external apparatus is used indoors, the external apparatus is put onto the electronic apparatus. Thus, a connector of the external apparatus is electrically connected to a connector of the electronic apparatus so as to achieve interchanging of data. It can extend the functions of the external apparatus by connecting the electronic apparatus to various external devices.
In order to stably lay the external apparatus on the electronic apparatus and to reduce manufacturing cost of the electronic apparatus, there is a requirement for limiting the size of the electronic apparatus. If a length size of the electronic apparatus is not long enough, the external apparatus will be overturned with respect to the electronic apparatus when a user presses the external apparatus, so that a connector of the external apparatus will get out of electrical connection with a connector interface of the electronic apparatus. If a width size of the electronic apparatus is not wide enough, the external apparatus will be overturned with the electronic apparatus when a user presses the external apparatus. In other words, at this time, the external apparatus can not be stably laid on the electronic apparatus. If the length size and/or the width size of the electronic apparatus are too great, although the external apparatus can be stably laid on the electronic apparatus, the manufacturing cost will be increased.